Summary of Work: Uranium miners have long been known to be at increased risk for lung cancer mortality. Risks for other cancers have not been consistently shown, possibly due to small numbers and limitations of studies based on death certificates. Risk has been most clearly demonstrated for miners exposed to very high levels of radon under extremely poor working conditions. The relevance of these results to more recent miners or to individuals exposed to radon in the home is not known. We have established a collaboration with investigators from the Czech Republic that gives us access to previously classified records of uranium miners exposed to modest amounts of radiation. Unlike previous studies, we will have information on smoking and dust exposure, both important potential confounding factors, as well as data from a population-based cancer registry to assess cancer incidence in addition to mortality. At total of 18,985 miners worked at least one year underground between 1949 and 1976. Vital status was determined for all but 511. Using a variety of sources, we have identified incident cancers and deaths through 1992 for the 16,585 miners known to be alive and still resident in the CR on 1/1/77. Standardized incidence and mortality ratios for all causes and individual causes will be calculated comparing miners to population rates. In addition, case-cohort analyses will evaluate detailed exposure measures as well as the impact of smoking and dust exposure on cancer risk. Preliminary analysis of suggests, in addition to the well-established lung cancer risk, increased risks for cancer of the larynx, digestive cancers, and leukemia. We have also used mine records in a case-control study of childhood cancers and find no association between paternal mining and cancer risk in offspring.